Insensitive Munition using Thermal Energy Harvesting

Midé proposes to develop an innovative approach to harvest energy from thermal excursions and use the harvested energy selectively to prevent the explosion of solid rocket motor during slow and fast cook-off vents. The thermal energy harvester is a Shape Memory Alloy device that responds slowly during temperature increases. The energy harvested is used to power a monitoring circuitry. The circuitry detects when a pre-determined maximum temperature is reached to fire a squib to trigger a venting system, which cuts the casing using a linear shape charge. Under normal ignition of the solid rocket the rate of temperature increase is so fast that the Shape Memory Alloy energy harvester cannot respond, allowing a thermal switch to be used to disable the venting system. Phase I will demonstrate that a system that fits within 2 cubic inches can trigger a venting system when the temperature inside the casing reaches 275 degrees F but would not fire the squib after reaching a temperature of 350 degrees F. Phase II will refine the concept and integrate the sensor unit into a thermally initiated venting system and demonstrate the technology in a slow and fast cook-off environment.